This invention relates generally to a phonograph record player, and more particularly, the present invention relates to a pickup arm control device used in an automatic record player.
In conventional automatic record players, the position of the pickup arm is detected to control the movement of the pickup arm so that the pickup arm is automatically moved to cause the reproduce stylus to be placed on a desired position on a phonograph record, and to cause the same to depart from the record when playback is completed. As a conventional device for controlling the pickup arm of a record player is known a pulse-count system in which the number of pulses corresponding to the moving amount or distance of the pickup arm is counted to detect the position of the pickup arm. In such a system, when it is detected that a lead-in position on a disc record is reached, the reproduce stylus is automatically engaged with the sound groove on the disc record, and when it is detected that a lead out position on the disc record is reached, the reproduce stylus is disengaged from the sound groove so as to move the pickup arm to the arm rest or a head position of a program to be reapeatedly reproduced. In such a record player, inertia of the pickup arm drive motor and encoder necessarily exists. Due to this inertia, the pickup arm does not stop at an instant when a stop command signal is fed to the pickup arm drive motor. In other words, the pickup arm overruns. However, the number of pulses produced from the encoder is counted for a time interval that the pickup drive motor is energized, and this results in miscounting because some pulses generated after the pickup drive motor is deenergized are not counted. As a result, the count which should indicate the positon of the pickup arm does not accurately indicate the actual pickup arm position. When such miscounting occurs, automatic control of the pickup arm is disturbed resulting in undesired movement of the pickup arm as will be described later in detail.